Is Matter Around Us Pure — Science STD 9 — Question

Which law states, that in a chemical compound, elements always combine in a fixed proportion?

Explain the formation of (i) sodium ion, and (ii) chloride ion, form their respective atoms giving the number of protons and number of electrons in each one of them. What is the reason for positive charge on a sodium ion and a negative charge on a chloride ion?

Draw a flow-chart for the schematic representation of different types of matter.

Explain why, diffusion occurs more quickly in a gas than in al iquid.

Which produces more severe burns: boiling water or steam? Why?

Compare an electron and a proton in respect of mass and charge.

A sample of vitamic C is known to contain 2.58 ×10²⁴ oxygen atoms. How many moles of oxygen atoms are present in the sample?

When ice at -10°C is slowly heated, temperature of ice gradually increases till 0°C, the temperature of the system remains constant when the ice change into water and then further rises. Explain the observation.

Which contains more heat, 1kg of ice at 0°C or 1kg of water at 0°C? Give reason for your answer.

Does the solubility of a substance change with temperature? Explain with the help of an example.